Replacing soft spots on floor

[massboater]

I have a few questions about replacing plywood on the deck of my 1985 wellcraft.

1.Do i need marine grade plywood or can pressure treated work.

2.How do I attach the plywood to the fiberglass crossbeams screws nails.

Thanks ahead of time.

[massboater]

ok

[warthog5]

marine plywood is a better product. No void's and is what I'd use. Don't use preasure treated plywood.
To install it cut the hole square and use a router to cut a rabbit around the permiter. Now cut your patch panel to the same size as the rabbit is cut. Then cut a rabbit on the patch panel. The rabbit's will fit together and give you more glue surface area.

Here's a sample of a piece cut in a console with a rabbit cut in it, to fill a hole.

http://www.classicmako.com/projects/xshark/bw21.htm

[greyg8r]

Yes, marine plywood IS better, but it is also much more expensive and a PITA to find here in Tampa (only available at boutique lumber yards and not available at Lowes or Home Depot). Plus, we are talking about a boat that is already 20 years old.

I would just use PT plywood. It will last 15 plus years, which I think would be sufficient. But, if you are restoring this boat back to cherry condition, I would use the marine plywood.

[Hawkeye]

I would use reg plywood with epoxy coating b4 I would use PT plywood. With PT plywood you will have trouble getting epoxy and sealers to stick.

[jmsllc]

marine grade plywood only...cut the spot square,when you make the cut cut it at a 45' angle-wider at the top,this will work like a giant cork,seal it in place using west system epoxy mixed with 403 micro fibers...be sure to coat the surfaces with plain west sysrem first,this will allow the wood to absorb the epoxy first and it will help the lamination process..use a weight to push the repair down in place untill the epoxy "kicks",wait the 8 hrs...this is the best way to repair a "soft spot"...if this is a repair to a non skid surfaced deck...after the west has kicked grind it flat fair it out than spray it with dura tec filler primer...this will fill the pin holes that will develop.if you're finishing the repair with gel cote,the dura tec will seperate the epoxy from the polyester gel-this will insure a reliable bond between the 2 surfaces.polyester products used over epoxy products have a potential to "shed" by using the dura tec it separates the 2 surfaces and avoids a potential compatibility issue.epoxy when it cures produces ammine blush,this has to be removed before using any thing on it...if the blush is removed,the gel will adhere,however the use of the dura tec will provide a much better adhesion!! hope this helps you!!!

[jmsllc]

almost forgot...try to avoid using polyester products on wood-the absorbtion factor isn't very good with the polyester products...remember this....the longer a product requires to cure the stronger,more reliable the bond.... the epoxy is much more expensive than the polyester products-but it's worth it...

[chris V]

pressure treated plywood will take months to dry out enough to use resins on.

I would also use regular plywood, one thickness thinner than your current floor, and once the wood is cut to size, laminate all exposed surfaces with a thin layer of resin and glass, including the old floor edges. once its cured enough to handle, make a dry fit. then resin and glass everything in place. adding a thinckening agent to the resin where the joint is, will give you a complete bond. yes, the thickener will weaken the resin some, but overall, because you have 100% contact on all surfaces, it will be much stronger.

yes, epoxy is much stronger, but your entire boat is made from polyester resin...